Racial/ethnic group disparities in HIV/AIDS are a critical public health issue in the US. These disparities are particularly dramatic with respect to injecting drug use. African-Americans constitute 13% of the US population and 52% of recent US injecting drug use AIDS cases;Hispanics constitute 14% of the US population and 24% of the injecting drug use AIDS cases. These disparities are not the result of more injecting drug users among African-Americans and Hispanics, but of higher rates of HIV infection among African- American and Hispanic IDUs in many areas of the country. Similar disparities-higher rates of HIV infection among ethnic minority IDUs-have also been observed in many foreign countries. Indeed the situation of ethnic minority IDUs in some developing countries can be considered a crisis, with extremely high incidence, prevalence and HIV-related mortality. Disparities have also been observed among non-injecting drug users, with ethnic minority group members having higher rates of HIV infection. The logical next step for addressing these disparities and this epidemiological conundrum is not another individual study, but a systematic review of the large number of relevant studies that have been conducted to date. Our proposed systematic review will use state-of-the-art methods and include the US and the international data on ethnic group differences in HIV infection among drug users. The specific aims include: Developing procedures for combining qualitative and quantitative data from multiple research studies of IDUs in a single geographic area into a "history of the HIV epidemic among IDUs" in that area. Determining the frequency of HIV epidemics in which substantial differences in HIV infection have and have not arisen in ethnic minority IDUs vs. ethnic majority IDUs in the US and internationally. Identifying potential causal factors that may generate substantial differences in HIV prevalence among racial/ethnic minority vs. ethnic majority IDUs. Identifying potential causal factors that may perpetuate or reduce differences in HIV infection among racial/ethnic differences over time. Identifying epidemiologic situations in which differences in HIV risk behaviors do or do not statistically "explain" differences in HIV infection among racial/ethnic groups of IDUs. The research will also create an extremely rich dataset on HIV infection among ethnic drug uses that will be made available for use by other researchers and HIV prevention service providers. The research addresses one of the most important aspects of HIV/AIDS-the frequent large disparities in HIV infection among ethnic groups in the US and in many other countries. The research will be an innovative application of state of the art methods for systematic review, including extensive searching for published and unpublished studies, quantitative coding of research reports, and applying meta-regression/hierarchical modeling to these problems. PUBLIC HEALTH RELEVANCE: Higher rates of HIV infection among African-American and Hispanic IDUs are a major health disparity in the US. African-Americans comprise 13% of the US population and 52% of injection drug use AIDS cases, Hispanics 14% of the populations and 24% of cases. Similar disparities, higher rates of HIV infection among ethnic minority IDUs, have also been observed in many foreign countries. An international systematic review and meta-analysis should greatly advance our understanding of these disparities and suggest how they might be ameliorated.